Double rake comminuting device



.Aug. 4, 1959 R. M. ARTHUR 2,897,967 7 DOUBLE RAKE COMM INUTING DEVICE Filed Sept. 9, 1955 4'Sheets-Sheet 1 Aug. 4, 1959 R. M. ARTHUR DOUBLE RAKE COMMINUTING DEVICE 4 Sheets-Sheet 2 Filed Sept. 9, 1955 Eula/22507," M725 77L, ans/MP Aug. 4, 1959 R; M. ARTHUR DOUBLE RAKE COMMINUTING DEVICE 4 Sheets-Sheet 3 Filed Sept. 9, 1955 g- 1959 R. M. ARTHUR I 2,897,967

DOUBLE RAKE COMMINUTINGDEVICE Filed Sept. 9, 1955 4 Sheets-Sheet 4 fl ji'flffi Lg' k 4 U I in MN I I I V fiwozzior wmwzx wmp i d a common (I -j)1f61i, but sephifitb p I rakes when 'thescrens are unequal in length. Tneir res are positioned at corresponding "ends Jot-their respective United Paten '1 2,897,967 DOUBLE COMlVIINUT-ING DEVICE Robert M. Arthur, 'FOlitl 'tlu Lac, "'Wis.-, 'assign'or "toChicago-Pump-Conipany, a corporationof Delaware Application Septeniber9f1955, Serial No. 533,362

This invention relates to a double rake comm-muting device having a cutting cylinder' positione d low "enough so that it is always submerged, to provide wet comminutionof sewage solids regardless bf variations in the ilow of sewage. V c In combining screening and comminuting devices used 'for the screening and cornminuation of sewage, it' has 'been customary to submerge the device in the sewage stream to provide for wet comminution of the sewage solids. nuting device is usually positioned to span the normal variations in sewage stream levels.

It has been proposed to provide a screening and cornminuting device embodying theme of a horizontally disposed, fixed level, rotatalble cutting cylinder positioned just below the normal liquid level offthe' sewages'tream. With this device a rake has been provided to 'move'solids intercepted by the screen up to thecylinder 'for c omminution. Whenever the liquid level falls below normal it is necessary to adjust 'thejposition of the cylinder or'to .co'm'mitlute the solids out of the. sewage stream until the liquid level again reaches its 'normalheight.

In accordance "with the present invention l'proyide a "combinedscreening and comminutingdevice'of the'type embodying the use of a horizontallyfdisposed ""ciitjting cylinder,"wherein the cylinder is positioned relatively low in the stream, substantially below the norrrral"liquid level, so that 'itreimains ubmerged "without further ad- .justment even during abnormally low liquid levelsof the sewagestream; Inthe'device of the present invention there are two screens, one extending"fromftheflowei edge of "the cutting cylinder to the bottom of the "inflnent channel, a'ndthe other extending'from the upper jedgeof the cylinder to"the'up'p'er possible lirnit'o'f the liquidl'evel of the sewage stream. The screens may be e th'er screens or ribbon screens, and may be either ver ally orangularly disposed. Theupper end'of thelowersereen is spaced from the lower end'ofthe npper-screenfte pro- "videa' hop eradjacentmeaning-cylinder. I V I "Separaterakcs are provided for each s reen itb iiive the'solids intercepted by eitherscreen to 'the idppjer.

If the screens are of eqpal length both f ts be rig units are i strokes-and are moved simultaneously in the same directions so that when the upper rake is in its '-'lowerrnost position the lower rake :is also-in its lowermostvposition.

lnthis arrangement the rakes transfer solids to th'e hopper alternately to maintain a fairly constant supply of solid "matter in the'liopper for c'oinrninution by flie cutting cyl- "rirderanarhe"combwiulwhich itcooperates. i

The s cturr'e 'rriy which theabove and 'other advantagesof the invention are attained will be described in the followiri g 'specification, "taken 'in conjunc- "tionwith the accom anying "drawings,"shqwingatpre- Iterred illu trati e embodiment 'o'fthe iiivefitionfi-n which: Figure 1 is afrori'televation of a com'minuting device embodying the invention, showing a pair of vertically sed screenswith separate rakes a cutting cylinnproirimity t'o thejadjacent ends o'fthe screens;

provided with slots (not shown) extending circumferentially of the cylinder.

-equal to the lateral distance between adjacent screen ereared ram l- 1g. 2 isa vertica l'fse'dtion al rewrite 2 -2 of Fig. 1, showing the hbpperbetween adjacent Ice 2,897,967

Pa-tented Aug. 4, 1959 6--6 of Fig. 4.

In such installations the screening and commimanner.

In the drawings, the-reference numeral 2 indicates a vertically disposed rectangular frame comprising -a pair of vertical channel members 3 and 4, a top member 5,

and a bottom member 6. The frame in the position shown faces the influent channel through which the sewage stream flows.

Bottommember '6 of the frame is secured to the bottom 7 of the influent sewage channel in any suitable A 'vertical flange 8 depends firom top member 5, and a similar flange 9 extends upwardly from bottom member 6. Upper flange 8 is provided with a series of transversely spaced apertures 10 and lower flange 9 is provided with a series of similar apertures 11. Both series of apertures arespaced uniformly. A pluralityof fiat ribbon screen elements 12 each has one'enlarged end a secured in one of the apertures 10-and similar elements K 13 have an enlarged end secured in one of the apertures 1 1. The free ends of the screen elements are spaced apart and these ends are held in *tensioning device's25 and 34.

Ahorizontally disposed cylindrical bearing housing 14 positioned between the 'tensioning devices on the 'eflluent sides of the screen elements, is provided with laterally extending legs 15 secured to the rear side of channel member-3 b-y=bol'ts 16. A'c uttingcylinder 17 is mounted for horizontalrotation in housing 14. Cylinder 17 is provided with a plurality of series of laterally projecting teeth 18 which cooperate with notches 19 in a cutting comb 20. The'portions of cylinder 17 between the series of teeth .18 may be irnperforate and may be provided with a roughened surface to cooperate with the opposed roughened s'urface of thecutting comb to aid in the comminution of solids. These in-between portionsma'y be The slo'ts preferably have a width elements 12 or 13 sothat they serve as the equivalent of additional screen openings toperrhit liquid sewage to 'flow therethrough. The slots intercept solids too large to pass through the screen which are carried by the cylinder to the comb. Ins'tead of slots, cylinder '17 may have larger openings bridged by screen elements which would also serve as the equivalent of additional screen surface. A cylinder provided with either slots or screened "openings as described above provides additional new capacity for the device. I

Comb 20 is secu'redto abraeket 21 mounted on housimg 14 and extends transversely of the cylinder with a notch-maligned with eachseries'of'teeth 13. As cylinder 17' is rotated, teeth 18 pass through notches 1? to comminute any solids engaged between the teeth and the comb. A shaft '22 extends from a motor (not shown) through a Sleeve '23 into engagement with gears (not shown) in 'a gear housing 24 mounted on housing 14 to rotate cylinder 17. The opposite end of cylinder 17 is similarly mounted at the opposite side of the frame, 'but the gears are provided at only one side of the frame.

- Cylinder--17 with its teeth l8 -a nd comb 20 may gbe replaced with'any other suitable type of comminuting deyice. Tensioning device 25 is mounted on frame 2 above cylinder 17 for holding the individual screen elements 12 under tension. The tensioning device comprises strip 26 secured at its opposite ends to each of channel members 3 and.4,and projecting rearwardly therefrom. A transverse bar 27 is adjustably secured to the bars 26 by means of screws 28. Bar 27 is provided with a notch 29 on its forward face adapted to receive one edge of each of a series of leaf springs 30. Leaf springs 30 are spaced transversely between channel members 3 and 4 with each spring aligned with one of the screen ribbons. The forward edge of each spring 30 is provided with a slit 31.

'Slits 31 are spaced to correspond with the transverse spacing of apertures 10. Each ribbon screen element 12 g having one end mounted in an aperture has its opposite end curled, as indicated at 32, and held edgewise in the slit 31 aligned with its aperture 10. An abutment 33, in the form of a rod secured to the bottom of strip 26, abuts the upper face of each spring 30 so that the desired tension can be applied to the screen elements 12 by adjusting the position of bar 27 relative to strip 26.

The other tensioning device 34 is mounted on frame 2 below cylinder 17 to hold the upper ends of screen elements 13. Tensioning device 34 is a duplicate of tensioning device 25 except that it is inverted. Accordingly tensioning device 34 will not be described in detail, and

the same reference numerals will designate the various parts.

A shield 35 comprising a metal sheet secured to the top of strip 26, and slotted to permit screen elements 12 to pass therethrough, as indicated at 36, extends around the lower ends of screen elements 12 and is curved rearwardly to form one wall of a hopper to receive solids pushed from the upper screen towards the cutting cylinder by a rake hereinafter described. The lower end of shield 35 terminates adjacent the upper edge of comb 20. A similar shield 37, slotted at 38 to permit screen elements 13 to pass therethrough, is secured to the bottom of strip 26 of tensioning device 34 and extends upwardly and Rake 47 comprises a wedge shaped bar extending transversely across the entire width of the lower screen on the influent side thereof, designed to rake solids intercepted by the screen to the hopper. The rake has a forwardly extending car 49 at each end. A screw or bolt 50 extends through ear 49 and link 45 to provide the pivotal connection between each end of the rake and the links 45.

The upper edge 51 of the rake, which comprises the thick edge of the wedge, extends at right angles to the screen surface as the rake is reciprocated vertically by block 42. As the rake approaches the upper limit of its travel it engages shield 37 and is held against the forward edge of the shield until it reaches said upper limit, which is substantially level with the uppermost portion of the shield. At this point the infiowing sewage washes the solids, which have been pushed upwardly along the screen surface by edge 51 of the rake, into the hopper formed by shields 35 and 37. As rake 47 is moved downwardly its thin edge tends to lift the solids that have been intercepted by the lower screen below the rake during the upward movement of the rake. The wedge shape of the rake permits it to move to its lowermost point without piling the solids into a mass at its lower edge. A curved surface in the form of fillet 52, extending forwardly from the upper edge of flange 9, prevents accumulation of solids 7 adjacent the bottom edge of the lower screen.

rearwardly around the upper ends of screen elements 13 to form the other hopper wall. The upper end of shield 37 terminates adjacent cylinder 17. The cylinder housings 14 form the sides of the hopper so that no solids can pass through the hopper into the efiluent channel except those that pass through notches 19 as they are comminuted by the interaction of teeth 18 and notches 19. If cylinder 17 is slotted or is provided with openings bridged by screens, solids may also pass through the cylinder. The slots or screen openings will be no larger than the openings between screen elements 12 or 13.

A hydraulic cylinder 39 is mounted vertically in the upper portion of each channel member 3 and 4. Since the stmcture of the hydraulic cylinders and the associated mechanism is the same in each of the channel members 3 and 4, the description will be directed to only one channel 2, but may be secured to the channel member in any 1 suitable manner. A piston rod 41 projects through the open lower end of cylinder 39 and is secured to a block 42 so as to move the block vertically as the piston rod is reciprocated. The vertical movement of block 42 is guided by a pair of guide bars 43 and 44 projecting inwardly from adjacent walls of the channel member. Guide bar 43 extends along the lower half of the channel member, and guide bar 44 extends substantially the entire length of the channel member. A link 45 is secured at one end to an extension 46 projecting laterally from block 42, and a rake 47 is pivotally secured to the opposite end of link 45. A flat spring 48 secured to the lower end of link 45 has one end bearing against the front surface of rake 47 adjacent its thin edge to urge the rake rear- A rod 53 secured to block 42 extends upwardly therefrom a distance equal to the length of the stroke of piston rod 41. A block 54 rigidly secured to the upper end of rod 53 is provided with a lateral projection 55 to which one end of a link 56 is secured. Block 54 is guided in its vertical movement by guide bar 44. A rake 57 is pivotally secured to link 56. Rake 57 is a duplicate of rake 47 except that the thick end of its wedge is at its lower end. The operation of rake 57 is the same as that of rake 47 except that as it moves downwardly its thick lower end pushes the solids downwardly until they are washed past the edge of shield 35 into the hopper. When the lower rake is in its uppermost position adjacent shield 37 the upper rake is also in its uppermost position adjacent the upper edge of the upper screen. When the lower rake is in its lowermost position the upper rake is also in its lowermost position adjacent shield 35. This arrangement causes the rakes to deliver their loads of solids fingers reach between adjacent screen elements, may be the same reference numerals.

used, if desired.

In Fig. 5 a modified embodiment of the invention is shown, in which the rectangular frame 2 is supported angularly by a pair of vertical support members 58. The structure of the embodiment of Fig. 5 is the same as that of the embodiment of Figs. 1 to 4, and is designated by The operation of the device of Fig. 5 is also the same as that of Figs. 1 to 4, and therefore the description thereof will not be repeated.

In both embodiments the cutting cylinder 17 is shown as being mounted at the mid-point of frame 2, but it will be understood that'it may be positioned at a lower point and the upper screen will then be longer than the lower screen. In such a structure it is preferred to have separate driving mechanisms for the upper and lower rakes. The driving mechanisms for the rakes are synchronized to move both rakes to the corresponding ends of their paths of travel simultaneously so that the rakes will still deliver the solids to the hopper alternately. The essential requirement of the position of the cutting cylinder is that it must be low enough to remain submerged at all times, and yet must be positioned above the bottom of the sewage channel to avoid any grit that may accumulate on the bottom of the sewage channel.

Both embodiments of the invention operate in the same manner. The inflowing sewage, up to the level of the uppermost edge of shield 37, engages the lower screen provided with the ribbon screen elements 13. The liquid sewage, and the solids that are sufiiciently small, pass between the screen elements, but the layer solids are intercepted by the screen elements. The lower rake 47 is periodically moved upwardly on the influent side of the screen to push the intercepted solids upwardly to the upper edge of shield 37. The inflowing sewage above the level of the lower end of the upper screen engages the screen elements 12. The liquid sewage, and the solids that are small enough, pass between screen elements 12, but the larger solids are intercepted thereby. The upper rake 57 is periodically moved downwardly on the influent side of the upper screen to push the intercepted solids downwardly to the lower edge of the upper screen.

The infiowing sewage at a level between the lower end of the upper screen and the upper end of shield 37 flows directly into the hopper formed by shields 35 and 37, and carries the solids from both rakes with it. If cylinder 17 is provided with slots the liquid sewage flows therethrough into the effluent flow. If cylinder 17 is imperforate, some of the liquid may flow between the lower portion of cylinder 17 and shield 37 and the rest will flow between the upper edge of the cylinder and comb 20. The solids are intercepted by the cylinder and are carried by teeth 18 to comb 20. The solids are comminuted by the interaction of teeth 18 and notches 19 of the comb, and then pass into the elfiuent stream.

Although I have described two preferred embodiments of my invention in considerable detail, it will be understood that the description thereof is intended to be illustrative, rather than restrictive, as many details of the structure may be modified or changed without departing from the spirit or scope of the invention. Accordingly, I do not desire to be restricted to the exact construction described.

I claim:

1. A comminuting device comprising a pair of screens interposed transversely in a sewage stream with the upper edge of one screen spaced from the lower edge of the other, a cutting cylinder and comb positioned in said stream between said screens, a rake mounted on each of said screens, and means to move said rakes alternately toward the edges of their respective screens adjacent said cutting cylinder, to thereby move sewage solids intercepted by each screen to said cutting cylinder at staggered intervals.

2. A comminuting device comprising a pair of screens interposed transversely in a sewage stream with the upper edge of one screen spaced from the lower edge of the other, a cutting cylinder and comb positioned in said stream between said screens, a hopper comprising a shield extending from the lower end of one screen to said cutting cylinder and a second shield extending from the upper end of said other screen to said cutting cylinder, the ends of said shields adjacent said cylinder being spaced apart to expose a peripheral portion of said cylinder between said shields, a rake mounted on each of said screens, and means to simultaneously move each of said rakes longitudinally of its screen in the same direction to move solids intercepted by said screen along the surface of said screen and into said hopper at staggered intervals.

3. A comminuting device comprising a rectangular frame extending transversely of a channel through which sewage flows, a pair of screens extending across said frame and spaced longitudinally of said frame relative to each other, a rake mounted on each of said screens, a common driving means operable to move each of said rakes longitudinally of its screen to move solids intercepted by said screen towards said other screen, a cutting with the space between said screens to engage solids moved from each of said screens by said rakes, and means cooperating with said cylinder to comminute solids engaged by said cylinder.

4. Acomminuting device comprising a pair of screens interposed transversely in a sewage stream with the upper edge of one screen spaced from the lower edge of the other, a cutting cylinder and comb positioned in said stream between said screens, a rake mounted on each of said screens, and means for simultaneously moving said rakes longitudinally of said screens, said rakes being positioned initially at corresponding ends of their individual paths of travel, whereby said rakes are adapted to alternately move solids intercepted by said screens from each screen to said cutting cylinder.

5. A communiting device comprising a pair of longitudinally extending screens positioned in longitudinally spaced relationship, a hopper extending rearwardly of said screens between the adjacent ends of said screens, comminuting mechanism positioned adjacent the rear end of said hopper, a rake mounted adjacent the front surface of each screen, and driving means for moving each of said rakes from the remote end of its screen to an end of said hopper, each of said rakes being adapted to push solids intercepted by its screen to said hopper, said driving means being adapted to move each of said rakes simultaneously in the same direction, whereby said rakes are adapted to deliver solids intercepted by said screens to said hopper at alternate intervals.

6. A comminuting device comprising a pair of longitudinally extending screens positioned in longitudinally spaced relationship, a hopper extending rearwardly of said screens between the adjacent ends of said screens, comminuting mechanism positioned adjacent the rear end of said hopper, a rake mounted adjacent the front surface of one of said screens, and driving means for moving said rake from the remote end of its screen to an end of said hopper, said rake being adapted to push solids intercepted by its screen to said hopper, said driving means comprising a hydraulic cylinder and a piston rod projecting therefrom, a block secured to said piston rod, said rake being secured to said block by a link, a rod secured to said block to move therewith, said rod having a length equal'to the length of stroke of said piston rod, a second block secured to the free end of said rod, and a rake secured to said second block by a link, whereby both rakes are adapted to be moved simultaneously in the same direction by said piston rod, said second rake being mounted adjacent the front surface of said other screen and adapted to push solids intercepted by said last mentioned screen to said hopper.

7. A comminuting device comprising a pair of coplanar screens interposed transversely in a sewage stream with the upper edge of one screen spaced from the lower edge of the other, a cutting cylinder and comb positioned in said stream between said screens, a wedge shaped rake mounted on each of said screens, and means to move each cylinder mounted on said frame and aligned-g hpriaontally of said rakes longitudinally of its screen, each of said rakes having the thick end of its wedge faced towards said cutting cylinder whereby each of said rakes is adapted to move the solids intercepted by its screen towards said cutting cylinder as the rake is moved in that direction.

References Cited in the file of this patent UNITED STATES PATENTS 

